Glycolysis Flashcards
Glycolysis occur in?
ALL CELLS cytoplasm
Glycolysis is the major pathway for?
glucose metabolism
Substrate for glycolysis?
Glucose
What is the end product of glycolysis
Pyruvate - during aerobic glycolysis, Lactate during anaerobic glycolysis
What is the rate limiting step in glycolysis?
Step 3 - conversion of fructose 6 phosphate to fructose 1,6 biphosphate
What is the rate limiting enzyme for glycolysis?
phosphofructokinase 1 (PFK-1)
Differentiate Aerobic from aneorobic glycolysis
Aerobic glycolysis happens in cells with mitochondria and adequate o2, with an energy investment of 2ATP, the end product is pyruvate. The latter happens in cells without mitochondria and o2, energy investment 4ATP, the end product is lactate,
What are the 3 important (irreversible and regulated) steps in glycolysis?
Step 1 - phosphorylation of glucose (hexokinase).
Step 2 - phosphorylation of fruc-6-phosphate (PFK-1). Step 3 - formation of pyruvate (pyruvate kinase)
What is unique with hexokinase?
it has high affinity(low km) for glucose, low vmax, present in most tissues
Hexokinase is inhibited by?
glucose-6-phosphatase (gluconeogenesis)
What are the 2 steps in glycolysis that produces ATP via substrate-level phosphorylation?
1,3-Biphosphoglycerate > 3-phosphoglycerate (phosphoglycerate kinase). Phosphoenolpyruvate > pyruvate (pyruvate kinase)
This is the step in glycolysis that produces NADH?
conversion of glyceraldehyde-3-phosphate > bisphophoglycerate ( g-3-p dehydrogenase)
What are the shuttle systems for aerobic glycolysis?
Malate aspartate shuttle (liver,kidney,heart). Glycerol phosphate shuttle (muscle,brain)
How many net ATP is produced if 1 mole of glucose undergoes Aerobic glycolysis?
8 ATP’s (MAS). 6 ATP’s (GPS)
What happens during arsenic poisoning?
arsenic inhibits pyruvate dehydrogenase
What is the most common enzyme defect in glycolysis?
pyruvate kinase deficiency which manifest as chronic hemolytic anemia
What are the alternate fate of pyruvate?
- pyruvate > acetyl coa (pyruvate dehydrogenase) krebs cycle. 2. pyruvate > oxaloacetate (pyruvate carboxylase) gluconeogenesis. 3. pyruvate > lactate (lactate dehydrogenase) anaerobic glycolysis. 4. pyruvate > ethanol (pyruvate decarboxylase) yeast
What are the co factors of pyruvate dehydrogenase?(maarte)
Thiamine pyrophosphate(B1), FAD (B2-Riboflavin), NAD (B3-Niacin), Coenzyme A (B5-pantothenic acid), Lipoic acid
What is the most common congenital cause of lactic acidosis?
pyruvate dehydrogenase deficiency
What co factor of pyruvate dehydrogenase is deficient during chronic alcoholism?
thiamine
